Disk tray locking device for an optical system

ABSTRACT

A disk tray shifting device for an optical disk player includes a bracket movable along the cross direction of a main base. The device includes a main base having a guide member, an up-down pivoting base secured to the main base, the up-down pivoting base having a protrusion projecting from one end thereof, a tray movable between a loaded position and an ejected position, and a bracket movable along the guide member in at least in a transverse direction with respect to a moving direction of the tray. The guide member is arranged in the cross direction of the main base. In one embodiment, a loading motor is attached to the bottom of the bracket, and a power transmission is installed on the bracket. It is possible to construct the disk tray shifting device simply and compactly by installing the loading motor and the power transmission in a single bracket.

[0001] This application is a continuation of copending application Ser.No. 09/927,400, filed on Aug. 13, 2001, which is a continuation ofapplication Ser. No. 08/928,639, filed on Sep. 12, 1997, the entirecontents of each of which are hereby incorporated by reference and forwhich priority is claimed under 35 U.S.C. §120, and this applicationclaims priority of Application No. 1996-39474 filed in Korea on Sep. 12,1996 under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a disk loading device for anoptical disk player, for example, a compact disk player or a digitalvideo disk player. One embodiment particularly relates to a disk trayshifting device wherein a loading motor for shifting the disk tray isinstalled movably along the cross direction of a main base, so that thedevice becomes compact and the reliability of power transmission thereofis improved.

[0004] 2. Description of the Prior Art

[0005] A conventional optical disk player includes a disk tray foraccommodating a disk, and a pickup for reading data recorded on thedisk. A conventional optical disk player also includes a disk loadingdevice including a loading motor for shifting the disk tray from theoutside of the player body to the inside thereof or from the inside ofthe body to the outside thereof that is mounted on one end of the mainbase, and a pickup driving motor for sliding the pickup that is mountedon the other end of the main base.

[0006] In the conventional disk loading device as described above,generally, a rack portion is formed on the underside of the disk tray,and a pinion to be rotated by the driving force transmitted from theloading motor is engaged with the rack portion. By this engagementbetween the rack portion and the pinion, the relative motion of the disktoward a turntable mounted on the pickup base is performed, so that theloading operation or the unloading operation is accomplished.Hereinafter, the structure and the operation of the conventional disktray shifting device will be described in detail with reference to FIG.1 through FIG. 3 of the appended drawings.

[0007]FIG. 1 is a perspective view showing an external appearance of anoptical disk player, FIG. 2 is a schematic top view showing a disk trayshifting device of the player, and FIG. 3 is a schematic front view ofthe disk tray shifting device. In the conventional disk tray shiftingdevice as shown in FIG. 1 through FIG. 3, a loading motor 2 is mountedon one end of the front portion of a main base installed inside of aplayer body 20, and the driving force of the motor 2 is transmitted toan idler gear 7 through a pulley 4 mounted on the upper end of the motor2, a belt 3 and a gear train. The gear train consists of a first gear 5and a second gear 6, and the idler gear 7 includes a pinion 7 a on theupper portion thereof, wherein the pinion 7 a is formed integrally withthe idler gear 7.

[0008] Referring to FIG. 2 and FIG. 3, an L-shaped arm 9 is insertedpivotably on the shaft 8 of the second gear 6, the idler gear 7 isinserted rotatably on the shaft 9 a formed on the first end portion 9 bof the arm 9, and a guide protrusion 10 is projected from the undersideof the second end portion 9 c. On the lower end of the shaft 8, acylindrical cam 11 having a cam groove 11 a engraved on the surfacethereof is fixedly mounted, and the lower end of the guide protrusion 10is inserted into a dimple 11 d formed on the upper surface of the cam 11through a curved shape guide slit 12. The guide slit 12 is formed on themain base 1.

[0009] On the other hand, on the underside of a disk tray 13, there isprovided a rack portion 14 along the longitudinal direction of the tray13, and the rack portion 14 is engaged with the pinion 7 a formedintegrally with the idler gear 7. The rack portion consists of alinear-shaped rack portion 14 a and a curved shape rack portion 14 b.

[0010] In FIG. 3, the reference number 15 indicates a protrusion, whichis formed on the front end of an up-down pivoting base (not shown) andwhich is inserted into the cam groove 11 a of the cam 11. The up-downpivoting base is pivotably mounted on the main base 1, and supports oneside of the pickup base not shown in FIGS. 1-3.

[0011] Now the loading operation of the disk tray shifting device willbe described.

[0012] Firstly, when the disk tray 13 is shifted outwards from theinside of the player, the disk D is placed on the tray 13. Thereafter,if the loading signal is applied to the disk tray shifting device, theloading motor 2 is actuated so that the pulley 4 mounted on the shaft ofthe motor 2 is rotated clockwise. At this time, since the driving forceof the motor 2 is transmitted to the pinion 7 a through the belt 3, thefirst gear 5, the second gear 6 and the idler gear 7, the pinion 7 aengaged with the rack portion 14 is rotated clockwise, so that the disktray 13 is shifted to the loading position. That is, when the pinion 7 ais rotated clockwise by the driving force transmitted from the loadingmotor 2, the disk tray 13 having the rack portion engaged with thepinion 7 a is shifted along the arrow direction, as shown in FIG. 2.Such shifting operation of the disk tray 13 is finished when the endportion of the linear-shaped rack portion 14 a reaches the pinion 7 a.Thereafter, when the tray 13 is shifted, the operation for placing thedisk D on the turntable is continued.

[0013] When the shift operation of the tray 13 is finished, if thepinion 7 a continues to rotate, the arm 9 is rotated counterclockwise onthe shaft 8 by the rotation of the pinion 7 a, and the pinion 7 a ismoved along the curved shape rack portion 14 b. Thus, the guideprotrusion projected from the underside of the second end portion 9 c ofthe arm 9 is also moved counterclockwise along the guide slit 12.

[0014] At this time, the cam 11 is rotated on the shaft 8 because thelower end of the guide protrusion 10 is inserted into a dimple lidformed on the upper surface of the cam 11. Accordingly, the protrusion15, which is formed on the front end of the up-down pivoting base andplaced in the first position 11 b of the cam groove 11 a, is moved alongthe cam groove 11 a towards the second position 11 c of the cam groove11 a. Therefore, the pickup base is moved upwards, and the disk D placedon the tray 13 is loaded on the turntable of the spindle motor, notshown. Here, the first position 11 b of the cam groove 11 a indicatesthe position of the protrusion 15 when the center hole of the disk D isnot inserted on the shaft of the turntable, and the second position 11 cof the cam groove 11 a indicates the position of the protrusion 15 whenthe center hole of the disk D is inserted on the shaft of the turntable.

[0015] The unloading operation of the disk tray shifting device isperformed according to the reverse order of the loading operation.

[0016] However, in the above described conventional disk tray shiftingdevice, a large number of components are necessary in order to achievepower transmission from the loading motor to the pinion. And since therotating radius of the idler gear and the space occupied with the beltare large, it is necessary to provide a large space for mounting theidler gear and the belt. Therefore, there are problems inminiaturization of the power transmission means and in the accuracy ofthe power transmission.

[0017] In addition, although not shown in FIGS. 1-3, it is necessary toprovide a separate locking device in order to prevent the tray frommoving freely after a loading operation in the conventional disk trayshifting device. However, the need for such a separate device alsoinhibits the miniaturization of the shifting device.

SUMMARY OF THE INVENTION

[0018] It is an object of the present invention to provide a novel disktray shifting device for the optical disk player in which a loadingmotor for shifting the disk tray with respect to a turntable is mountedmovably in the cross direction of a main base in order to minimize theinstallation space of components.

[0019] Another object of the present invention is to provide a disk trayshifting device which can transmit the driving force of a loading motorto the disk tray by minimizing power transmission stages so as tocontrol the shifting operation of the disk tray precisely.

[0020] A further object of the present invention is to provide a disktray shifting device which is compactly and simply constructed byinstalling the loading motor and the power transmission means in asingle bracket and by minimizing the installation gap betweencomponents.

[0021] Another object of the present invention is to provide a disk trayshifting device which is able to improve the assembling workability andto interchange the components easily by the compact construction.

[0022] Still another object of the present invention is to provide adisk tray shifting device in which a locking device for preventing thetray from moving freely after a loading operation is formed on thebracket so as to accomplish a loading operation and a locking operationsimultaneously.

[0023] A further object of the present invention is to provide a disktray shifting device in which the upward movement of a pickup base andthe crosswise movement of the loading motor can be accomplishedtogether.

[0024] Another object of the present invention is to provide a disk trayshifting device wherein a cable for supplying electrical signals to theloading motor can be easily connected without any interference betweenother components.

[0025] Still another object of the present invention is to provide adisk tray shifting device wherein a sensor for detecting the position ofthe loading motor is simply constructed, and yet wherein a signaltransmission device for supplying electrical signals to a spindle motorand the like is compactly and simply connected.

[0026] These objects are achieved according to the present invention byproviding one embodiment of a disk tray shifting device which isarranged in the optical disk player, and which comprises: a main base; aguide bar arranged on the main base along the cross direction of themain base; a bracket mounted slidably on the guide bar and being movedalong the guide bar, wherein the bracket includes a guide groove on oneside thereof; a loading motor attached to the bottom of the bracket; atray including a rack portion formed on the underside thereof; a powertransmission device installed on the bracket and transmitting thedriving force of the loading motor to the tray, wherein the powertransmission device includes an intermediate gear and an idler gear; anda circuit portion mounted on one side of the main base.

[0027] In the present invention, the rack portion formed on theunderside of the tray includes a longitudinal rack formed along thelongitudinal direction of the tray and a lateral rack formed along thecross direction of the tray. Therefore, when a pinion projected from theupper surface of the idler gear is engaged with the longitudinal rackand that pinion begins to rotate, the tray is shifted along thelongitudinal direction of the main base. Furthermore, when the pinion isengaged with the lateral rack and that pinion begins to rotate, thebracket is moved along the guide bar in the cross direction of the mainbase.

[0028] When the bracket is moved along the guide bar, an up-downpivoting base supporting one side of a pickup base is pivoted on theshaft upwards or downwards. Thus, a turntable mounted on the pickup baseis either inserted into the center hole of the disk, or removed from thecenter hole.

[0029] And when the bracket is moved along the cross direction of themain base, a locking device formed on the bracket is put into contactwith a stopper formed on the underside of the tray in order to preventthe tray from moving freely.

[0030] In addition, the circuit portion and the loading motor areinterconnected with the signal transmission device, and the circuitportion includes a sensor for detecting the position of the bracket.

[0031] Advantages of the present invention will become more apparentfrom the detailed description given hereinafter. However, it should beunderstood that the detailed description and specific examples, whileindicating preferred embodiments of the invention, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the invention will become apparent to those skilledin the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a perspective view showing an external appearance of aconventional optical disk player;

[0033]FIG. 2 is a schematic top view showing a conventional disk trayshifting device;

[0034]FIG. 3 is a schematic front view showing the conventional disktray shifting device;

[0035] FIGS. 4A-4C are exploded schematic top views showing a disk trayshifting device in accordance with one embodiment of the presentinvention;

[0036]FIG. 5 is a cross-sectional view taken on lines 5A-5A in FIG. 4B;

[0037]FIG. 6 is a rear view of a bracket shown in FIG. 4B;

[0038]FIG. 7A is a schematic top view showing the unloading state of thedisk tray shifting device in accordance with the present invention;

[0039]FIG. 7B is a schematic view illustrating the relative positionbetween the bracket and the circuit portion of FIG. 7A;

[0040]FIG. 7C is a side view of the bracket and the pickup base of FIG.7A;

[0041]FIG. 8A is a schematic top view showing the progress of theloading operation of the disk tray shifting device in accordance withthe present invention;

[0042]FIG. 8B is a schematic view illustrating the relative positionbetween the bracket and the circuit of FIG. 8A;

[0043]FIG. 9A is a schematic top view showing the complete state of theloading operation;

[0044]FIG. 9B is a schematic view illustrating the relative positionbetween the bracket and the circuit portion of FIG. 9A;

[0045]FIG. 9C is a side view of the bracket and the pickup base of FIG.9A;

[0046]FIGS. 10A and 10B are a schematic top view and a front view of thedisk tray, respectively; and

[0047]FIGS. 11A and 11B are schematic views illustrating the assemblingstructure between a main base and the disk tray.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0048] The present invention will now be described in detail withrespect to an embodiment shown by the appended drawings.

[0049] Referring to FIG. 4A through FIG. 6, the disk tray shiftingdevice in accordance with the present invention comprises a tray 21 foraccommodating a disk, a bracket 22 having a loading motor 31 and a powertransmission device, a circuit portion 23 mounted on one side of a mainbase 16, and an up-down pivoting base 24 supporting one side of a pickupbase.

[0050] The tray 21, which is arranged on the main base 16, has a concaveplate 25 for accommodating the disk, an L-shaped rack 26, a first guidegroove 27, a second guide groove 28 and a stopper 29. The concave plate25 and the L-shaped rack 26 are formed on the underside of the tray 21.The first guide groove 27 is extended on the underside of the tray 21along the rack 26, and the first guide groove 27 has almost the sameshape as the L-shaped rack 26. At the central portion of the concaveplate 25, a stopper 29 is projected from the underside of the tray 21.The rack 26 includes a longitudinal rack 26 a being extended along thelongitudinal direction of the tray 21, a lateral rack 26 b beingextended along the cross direction of the tray, and a slanted rack 26 c.The second guide grooves 28 are formed at both sides of the uppersurface of the tray 21.

[0051] FIGS. 11A-11B are schematic views illustrating the assemblingstructure between the main base 16 and the tray 21. As shown in FIGS.11A-11B, the second guide grooves 28 are engaged with protrusions 18formed on the main base 16, and the upper side portions of the disk 21contact the lower surfaces of protrusions 17 formed on each side of themain base when the main base 16 and tray 21 are engaged.

[0052] The bracket 22 is mounted movably on a guide bar 30 along thecross direction of the main base 16. The guide bar 30 is fixed in thevicinity of the front end portion of the main base 16. The loading motor31 is mounted under the bracket 22, and a motor gear 33 is inserted on amotor shaft 32 which is projected upwards from the bracket 22. On thebracket 22, a first shaft 34 is formed integrally with the bracket 22and is projected upwards from the tipper surface of the bracket. Themotor gear 33 is engaged with a large gear 35 a of an intermediate gear35, which is mounted rotatably on the first shaft 34.

[0053] On the lower portion of the first shaft 34, one end of an armwhich has a second shaft 38 at the other end thereof is insertedrotatably, while an idler gear 36 is disposed on the second shaft 38.The idler gear includes a large gear 36 a and a small gear 36 b. Thesmall gear 36 b acts as a pinion engaging with the rack 26, and thelarge gear 36 a is engaged with the small gear 35 b of the intermediategear 35. The upper end 38 a of the second shaft 38 is extended above theidler gear 36.

[0054] Referring to FIG. 5, a guide protrusion 47 is extended from thesecond shaft 38, and is inserted into a guide slit 39 which is piercedon the right side of the bracket 22. On the left end of the bracket 22,there is formed a protrusion 40 for operating a switch disposed on thecircuit portion 23. As shown in FIG. 6, a guide cam groove 48 isengraved on the rear surface of the bracket 22 and surrounded by a rib22 a, and a locking device 41 is projected from the upper end of thebracket 22.

[0055] Referring again to FIG. 4B, the circuit portion 23 is disposed onone side of the main base 16, and a position sensor for detecting theposition of the bracket 22 is mounted on the circuit portion 23. In thisembodiment, a push switch 43 is used as the sensor, the push switch 43coming into contact with the protrusion 40 which is formed on thebracket 22. On the circuit portion 23, connecting members 42 a and 42 bare provided. A signal transmission device 42 c for supplying thesignals to the loading motor 31 is connected to the connecting member 42b, and a signal transmission device 42 d for supplying the signals tothe spindle motor (not shown), which is used to drive the turntable, isconnected to the connecting member 42 a. The circuit portion 23 iselectrically connected to the control board disposed in the player bodyvia a signal transmission member, not shown. In this embodiment, theflexible cables are used as the signal transmission device.

[0056] The up-down pivoting base 24 has a U-shape, and both shafts 44thereof are secured rotatably to the main base 16. On the front end ofthe up-down pivoting base 24, there is formed a protrusion 45 which isengaged with the guide cam groove 48 of the bracket 22, as shown in FIG.6. The up-down pivoting base 24 supports one side of the pickup base 46,and the shafts 44 are secured rotatably to the main base 16, so that thepickup base 46 moves upwards and downwards when the up-down pivotingbase 24 is pivoted on the shafts 44.

[0057] The structures of the bracket 22 and the power transmissiondevice, and the engaging relation between gears in a movable drivingportion DP will be understood from FIG. 5 and FIG. 6.

[0058] As shown in FIG. 5, the driving force of the loading motor 31 istransmitted to the rack 26 by way of the intermediate gear 35 engagedwith the motor gear 33, the idler gear 36 and the pinion formedintegrally with the idler gear 36. The idler gear 36 inserted on thesecond shaft 38 of the arm 37 is rotated around the first shaft 34, andthe rotating range is defined by the moving range of the protrusion 47inserted in the guide slit 39. That is, the rotating range of the arm 37is restricted by the piercing length of the guide slit 39.

[0059] Referring to FIG. 6, the guide cam groove 48 is engraved on therear surface of the bracket 22. The protrusion 45 projected from thefront side of the up-down pivoting base is inserted into the guide camgroove 48. The guide cam groove 48 includes an upper horizontal portion48 a, a lower horizontal portion 48 b and a slant portion. The slantportion of the guide cam groove 48 includes a first slant portion 48 cwith steep slope and a second slant portion 48 d with gentle slope.

[0060] Now the operation of the disk tray shifting device in accordancewith the present invention will be described.

[0061]FIG. 7A is a schematic top view showing the unloading state of thedisk tray shifting device, FIG. 7B is a view illustrating the relativeposition between the bracket 22 and the circuit portion 23, and FIG. 7Cis a side view of the bracket 22 and the pickup base 46.

[0062] As shown in FIG. 7A, the bracket 22, including the loading motor31 and the power transmission device is located at the right side of themain base 16 in the eject state. At this time, the pinion 36 b of theidler gear 36 is engaged with the rear end portion of the longitudinalrack 26 b, and the second shaft 38 is inserted into and guided by thefirst guide groove 27 of the tray 21. When the tray 21 is in the ejectstate, the protrusion 45 formed on the up-down pivoting base 24 islocated in the lower horizontal portion 48 b so that the front side ofthe pivoting base 24 keeps the down position.

[0063] Thereafter, when the disk is placed on the concave plate 25 ofthe tray 21 and the loading signal is applied to the disk tray shiftingdevice, the loading motor 31 begins to rotate and the driving force ofloading motor 31 is transmitted to the pinion 36 b by way of theintermediate gear 35 and the idler gear 36. Since the pinion 36 d isengaged with the rack 26, the tray 21 begins to shift toward theturntable along the arrow direction A.

[0064] On the other hand, since the upper end 38 a of the second shaft38 is guided by the first guide groove 27 (see FIG. 7B), rotation of thearm 37 in which the idler gear 36 is mounted thereon is blocked so thatrotation of the idler gear 36 is also blocked, and the bracket 22 islocated at the right side of the main base. When the pinion 36 b reachesthe front end of the longitudinal rack 26 a, the shifting operation ofthe tray 21 is stopped. Then, when the pinion 36 b is continuouslyengaged with the lateral rack 26 b by the continuous driving of theloading motor 31, the bracket 22 moves along the guide bar 30 in thecross direction. FIG. 8A shows the progress of the loading operationwhen the bracket 22 moves along the guide bar 30.

[0065] As shown in FIG. 8B, since the bracket 22 moves along the arrowdirection B as long as the pinion 36 b is engaged with the lateral rack26 b and continues to rotate, the protrusion 45 inserted in the guidecam groove 48 of the bracket 22 passes through the first slant portion48 c with the steep slope and is located in the second slant portion 48d with the gentle slope so that the up-down pivoting base 24 begins topivot upwards on the shafts 44.

[0066] On the other hand, when the protrusion 45 passes through thefirst slant portion 48 c, the speed of the up-down pivoting base 24increases because the disk does not come into contact with theturntable. But when the protrusion 45 passes through the second slantportion 48 d, the disk comes into contact with the turntable. Thus, inorder to place the disk on the turntable safely, the speed of thepivoting base 24 must be reduced. Thereafter, when the locking device 41projected from the upper end of the bracket 22 comes into contact withthe stopper 29 formed on the underside of the tray 21, the shifting ofthe tray 21 in the inverse direction of the arrow direction A isprevented. That is, the stopper 29 prevents the ejection of the tray 21due to a careless mistake of the user or an external impact when theloading operation of the tray 21 is finished.

[0067] Thereafter, by the continuous rotation of the loading motor 21,the bracket 22 is continued to move in the arrow direction B as long asthe pinion 36 b moves on the slant rack 26 c. When the pinion 36 bbegins to engage with the slanted rack 26 c, the arm 37 including theidler gear 36 thereon is rotated clockwise on the first shaft 32. Atthis time, the guide protrusion 47 projected from the arm 37 is guidedby the guide slit 39 formed on the bracket 22, and the upper end 38 a ofthe second shaft 38 is guided by the first guide groove 27.

[0068] When the pinion 36 b reaches the end of the slant rack 26 c, theloading operation will be finished. FIG. 9A is a schematic top viewshowing the complete state of the loading operation, FIG. 9B is aschematic view illustrating the relative position between the bracket 22and the circuit portion 23 after finishing the loading operation, andFIG. 9C is a side view of the bracket 22 and the pickup base 46. Asshown in FIG. 9B, when the protrusion 40 of the bracket 22 comes intocontact with the switch 43 mounted on the circuit portion 23, rotationof the loading motor 31 is stopped by the operation of the switch 43. Asdescribed above, when the pinion 36 b reaches the end of the slant rack26 c, the slant rack 26 c prevents the movement of the driving portionDP in the arrow direction B or the inverse direction of the arrowdirection B.

[0069] At this time, since the protrusion 45 of the up-down pivotingbase 24 is located in the upper horizontal portion 48 a of the guide camgroove 48, the pivoting base 24 and the pickup base 46 are finishedmoving upward. Thus, the turntable is inserted into the center hole ofthe disk so that the disk is loaded on the turntable.

[0070] The unloading operation of the disk tray shifting device inaccordance with the present invention is performed according to thereverse order of the loading operation.

[0071] According to the present invention as described above, it ispossible to minimize the installation space of components by mountingthe loading motor movable along the cross direction of the main base andto transmit the driving force of the loading motor to the disk trayeffectively by minimizing power transmission stages.

[0072] Also, it is possible to construct the disk tray shifting devicesimply and compactly by installing the loading motor 31 and the powertransmission means in a single bracket 22.

What is claimed is:
 1. A disc tray locking device for an optical system,comprising: a main base having a guide member; an up-down pivoting basesecured to said main base, said up-down pivoting base having aprotrusion projecting from one end thereof; a tray movable between aloaded position and an ejected position, said tray having a stopperformed on one side thereof; and a bracket movable along said guidemember in at least a transverse direction with respect to a movingdirection of said tray, said bracket having a guide cam groove engravedon one surface thereof, said guide cam groove being engaged with saidprotrusion of said up-down pivoting base, and said bracket having alocking portion which contacts said stopper for preventing furthermovement of said tray beyond said loaded position.
 2. The disc traylocking device according to claim 1, wherein said locking portion is aprotrusion projected from the upper side of said bracket.
 3. The disctray locking device according to claim 1, wherein said up-down pivotingbase is lifted by a moving operation of said bracket.
 4. The disc traylocking device according to claim 1, further comprising a motor forshifting said tray between the loaded position and the ejected position.5. The disc tray locking device according to claim 4, wherein saidbracket is moved by a driving force of said motor.
 6. The disc traylocking device according to claim 1, wherein said up-down pivoting baseincludes a pickup unit and a spindle motor for driving a turntable.
 7. Adisc tray locking device for an optical system, comprising: a main basehaving a guide member; an up-down pivoting base secured to said mainbase, said up-down pivoting base having a protrusion projecting from oneend thereof; a tray movable between a loaded position and an ejectedposition, said tray having a stopper formed on one side thereof; abracket movable along said guide member in at least in a transversedirection with respect to a moving direction of said tray, said brackethaving a guide cam groove engraved on one surface thereof, said camguide groove being engaged with said protrusion of said up-down pivotingbase; and a switch controlled between on and off positions based on aposition of said bracket.
 8. The disc tray locking device according toclaim 7, wherein said switch is on/off controlled based on said positionof said bracket which is varied when said protrusion moves along saidguide cam groove.
 9. The disc tray locking device according to claim 7,wherein said switch is on/off controlled based on said position of saidbracket which is varied when said bracket moves along said guide member.10. The disc tray locking device according to claim 7, wherein saidup-down pivoting base is lifted by a moving operation of said bracket.11. The disc tray locking device according to claim 7, furthercomprising a motor for shifting said tray between the loaded positionand the ejected position.
 12. The disc tray locking device according toclaim 11, wherein said bracket is moved by a driving force of saidmotor.
 13. The disc tray locking device according to claim 7, whereinsaid up-down pivoting base includes a pickup unit and a spindle motorfor driving a turntable.
 14. A disc tray locking device for an opticalsystem, comprising: a main base having a guide member; an up-downpivoting base secured to said main base, said up-down pivoting basehaving a protrusion projecting from one end thereof; a tray movablebetween a loaded position and an ejected position, said tray having astopper formed on one side thereof; a bracket movable along said guidemember in at least a transverse direction with respect to a movingdirection of said tray, said bracket having a locking portion whichcontacts said stopper for preventing further movement of said traybeyond said loaded position; and a switch controlled between on and offpositions based on a position of said bracket.
 15. The disc tray lockingdevice according to claim 14, wherein said switch is on/off controlledbased on said position of said bracket which is varied when said bracketmoves along said guide member.
 16. The disc tray locking deviceaccording to claim 14, wherein said locking portion is a protrusionprojected from the upper side of said bracket.
 17. The disc tray lockingdevice according to claim 14, wherein said up-down pivoting base islifted by a moving operation of said bracket.
 18. The disc tray lockingdevice according to claim 14, further comprising a motor for shiftingsaid tray between the loaded position and the ejected position.
 19. Thedisc tray locking device according to claim 18, wherein said bracket ismoved by a driving force of said motor.
 20. The disc tray locking deviceaccording to claim 14, wherein said up-down pivoting base includes apickup unit and a spindle motor for driving a turntable.